ACPAtmospheric Chemistry and PhysicsACPAtmos. Chem. Phys.1680-7324Copernicus PublicationsGöttingen, Germany10.5194/acp-13-7441-2013The thermodynamic state of the Arctic atmosphere observed by AIRS: comparisons during the record minimum sea ice extents of 2007 and 2012DevasthaleA.1SedlarJ.1KoenigkT.2FetzerE. J.31Atmospheric Remote Sensing Unit, Research and Development Department, Swedish Meteorological and Hydrological Institute (SMHI), Norrköping, Sweden2Rossby Center for Climate Research, Swedish Meteorological and Hydrological Institute (SMHI), Norrköping, Sweden3JPL/CALTECH, NASA, Pasadena, California, USA02082013131574417450This work is licensed under a Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/This article is available from http://www.atmos-chem-phys.net/13/7441/2013/acp-13-7441-2013.htmlThe full text article is available as a PDF file from http://www.atmos-chem-phys.net/13/7441/2013/acp-13-7441-2013.pdf

The record sea ice minimum (SIM) extents observed during the summers of 2007
and 2012 in the Arctic are stark evidence of accelerated sea ice loss during
the last decade. Improving our understanding of the Arctic atmosphere and
accurate quantification of its characteristics becomes ever more crucial, not
least to improve predictions of such extreme events in the future. In this
context, the Atmospheric Infrared Sounder (AIRS) instrument onboard NASA's
Aqua satellite provides crucial insights due to its ability to provide 3-D
information on atmospheric thermodynamics.
Here, we facilitate comparisons in the evolution of the thermodynamic state
of the Arctic atmosphere during these two SIM events using a decade-long AIRS
observational record (2003–2012). It is shown that the meteorological
conditions during 2012 were not extreme, but three factors of preconditioning
from winter through early summer played an important role in accelerating
sea ice melt. First, the marginal sea ice zones along the central Eurasian
and North Atlantic sectors remained warm throughout winter and early spring
in 2012 preventing thicker ice build-up. Second, the circulation pattern
favoured efficient sea ice transport out of the Arctic in the Atlantic sector
during late spring and early summer in 2012 compared to 2007. Third,
additional warming over the Canadian archipelago and southeast Beaufort Sea
from May onward further contributed to accelerated sea ice melt. All these
factors may have lead the already thin and declining sea ice cover to pass below
the previous sea ice extent minimum of 2007. In sharp contrast to 2007,
negative surface temperature anomalies and increased cloudiness were observed
over the East Siberian and Chukchi seas in the summer of 2012. The results
suggest that satellite-based monitoring of atmospheric preconditioning could
be a critical source of information in predicting extreme sea ice melting
events in the Arctic.